The present invention relates to liquid circulation systems, and more particularly to a system and method for automatically turning off a spa circulation system in certain situations.
Spas, also known as hot tubs, whirlpools, etc., utilize relatively powerful pump driven circulation systems to inject powerful streams of water into the spa. This water stream, often combined with air, is directed onto the user, thereby creating a pleasing, sometimes therapeutic effect. The circulation system providing such water streams draws water from the spa itself through a drain typically located at the bottom or wall of the spa. Because of the relatively high volume of water required to produce the desired pressure in the resulting water streams, (typically in the range of 50-100 gallons per minute) water is drawn by the circulation system through the drain opening at a relatively high velocity.
To ensure that foreign objects are not drawn into the drain, a drain cover is usually employed having small holes to permit only water to enter the circulation system. Operation of the spa without the drain cover in place could create a number of potential problems. For example, foreign objects brought into the circulation system could damage the pump or other components in the circulation system. Moreover, because of the relatively high velocity of the water drawn into the drain, there is a possibility of users of the spa having limbs or hair drawn into the drain.
Nevertheless, it has been found that users of spas sometimes remove the drain covers for cleaning and may neglect to replace the cover and operate the spa without the cover in place. To prevent this from occurring, spas in the United States generally comply with the Consumer Product Services, Underwriter Laboratory (UL) or American National Standards Institute (ANSI) requirements that a spa drain cover be removable only with the use of tools. For example, the drain cover may be secured by one or more screws. It is felt that this requirement lessons the likelihood that a spa will be used without the drain cover in place. For example, with this requirement it is less likely that children playing in the spa would remove the drain cover during use.
Yet even with the requirement that spa drain covers be secured in this manner, it is still possible for a user to fail to replace the drain cover and to operate the drain without the cover in place. This could result in the aforementioned problems. Furthermore, it has been found that even with the drain covers in place, it is unlikely but possible for a person's hair to be drawn into the drain. Once this occurs, the hair may be difficult to remove due to the relatively strong suction force in the drain opening, and also due to the possibility that they hair may become entangled in the drain cover openings. Once the person's hair is entangled in the drain cover, drain covers requiring tools to remove make the situation worse since the person will not normally have an opportunity to obtain a tool to remove the drain cover. Additionally, spa drain openings often employ an anti-vortex structure near the drain cover which provides an additional way for hair to become entangled.
Thus while hazards still exist with drain covers that require tools to remove, it is generally felt (and in fact required) that drain covers be secured in this way because the risk of user entrapment is lower than it would be if drain covers were easily removed.
A further problem which stems from the above discussed situation, is that the flow rate in spas is frequently limited (for example, to 50 gallons per minute) to thereby reduce the suction force in any effort to make spas safer. As a result of limited flow rates, the water pressure producing the water jets to provide recreational and therapeutic benefits is necessarily limited.
Thus, it would be desirable to provide a spa which further reduces or eliminates the possibility of a person's hair becoming entrapped in the spa drain. It would also be desirable to provide a spa drain cover which reduces the possibility of hair entrapment in the spa drain. It would also be desirable to provide a spa which reduces such risks to the user whether the drain cover is in place or not. Furthermore, it would be desirable to provide a spa which can safely utilize a higher flow rate than is currently used.